I've been looking at these two CPU's but I don't know which one is better can someone please help me with this.
Those are very different cpu's.The FX-4100 is AM3 socket while A8 5600k is FM2 socket. So you need different motherboards
A8 5600k is APU or accelerated processing unit, its like cpu+gpu in one small chip :)
FX-4100 is your normal every day cpu with four cores.
I know but I want to know what would be the most effcient for rendering :)
HAHA You should asked more specific question and save me some typing :P
FX-4100 is more effcient for rendering.
Why do you want to buy the 4 core bulldozer cpu? If you are really low on budget, get an athlon 750K, which is much better for a marginal price difference. Not to mention, it is FM2 if you already have a motherboard.
1+ For this!
yeah but I live in New Zealand and they don't have any quad core athlons :(
yea sorry dude
Do you already have a motherboard? Take a look at Fx 6300 or 4300 at least. Seriously, a 4100 is a piss poor cpu. Even the phenom II's were better than bulldozer cpus.
If you are looking for a cheap AMD cpu for rendering the older amd phenom ii x4/x6 cpu's are stronger than both of those cpus and thay have 4 / 6 real cores and not piledriver/bulldozer modules.
Outherwise look for a intel xeon (cheaper vershons of i5/i7 cpu's)
The A8-5600k is piledriver and the FX4100 is bulldozer, out of those two the APU would actually be better but both are not great choices for rendering. You're going to need more oomph than that to really get good value out of your rig for that use-case. An older Phenom II x6 (if you can find them) would be good or an FX6300 or an overclocked 8120(roughly same price as newer 6core) would be much better choices. Cinebench scores will show you the rendering power difference between each of these and neither the A8-5600k or FX4100 can score very well whatsoever ...
Better question is which is more powerful, the Phenom II X4 965 Black or the FX 4300 or the A8-5600k? Honestly, I get the feeling that in everyday use, at similar clock speeds, the k10 based Phenom II will actually perform better than the others because it has a discrete floating point unit for every algorithmic core that it claims to have. It says it has four cores, it actually has four cores with four discrete threads. The Phenom II X6 series are also made like this from the k10 series of core architecture. Conveniently, these chips are compatible with the current generation of AM3+ boards and also natively support DDR3 RAM, although the native clock rate is only 1066 MHz, so expect to raise this in the BIOS to a more respectable rate.